The Food and Drug Administration (FDA) has issued a warning about a dietary sports supplement marketed under the names Blue Nitro, Firewater and Invigorate after an incident that hospitalized the National Basketball Association's Tom Gugliotta.

The Phoenix Suns forward suffered a near-fatal seizure December 17 and was subsequently hospitalized.

A team doctor said a supplement containing gamma butyrolactone, or GBL, which Gugliotta had taken twice just days before the incident, most likely caused the seizure.

GBL-related products have been associated with the reports of at least six deaths, prompting numerous safety warnings from the FDA.

The FDA considers GBL an unapproved drug. It therefore is illegal to manufacture and distribute for human consumption.

GBL is available as a liquid or powder under many different brand names, including Renewtrient, Revivarant, Blue Nitro Vitality, Insom-X and GH Revitalizerat. It typically is sold through the Internet and at gyms and fitness centers, as well as in some health-food stores.

The supplement is marketed as an aid to insomnia, as a fitness and weight-loss product and for stress reduction.

The FDA has issued public warnings that GBL can cause "dangerously low respiratory rates," requiring a doctor to insert a breathing tube into the patient's throat, as well as unconsciousness, coma, vomiting, seizures and even death.

According to the Los Angeles Times, as of December 16, the day before Gugliotta's seizure, the FDA had tallied 116 arrests, 55 convictions and 38 GBL-related indictments handled by the agency's Office of Criminal Investigations.

As of December 9, the FDA had received reports from medical professionals and hospitals of 242 incidents, including six deaths and 191 cases in which medical intervention was required.

The body breaks GBL down into gamma hydroxybutyric acid, or GHB, a so-called date-rape drug that is colorless, tasteless and can be added to alcohol to produce an unconscious state.

In 1990, the FDA banned the use of GHB and warned consumers to stop using it because of health risks.

Authorities believe some companies then began producing GBL instead. After the FDA warned about that substance, companies began making BD, which stands for 1,4 butadeniol, a chemically similar compound sold as a sleep aid, party drug and muscle builder.

GBL products also may be labeled as containing 2(3H)-furanone dihydro, butyrolactone, gamma-butyrolactone, 4-butyrolactone, dihyro-2(3H)-furanone, 4-butanolide and tetrahydro-2-furanone.

An FDA spokesperson told the Los Angeles Times that there was no research to demonstrate the safety or effectiveness of most of the GBL-like compounds.

The NCAA position on dietary supplements is one of caution. These substances are not regulated by the Food and Drug Administration, and manufacturers are not legally bound to disclose all ingredients.

Some of these supplements may contain NCAA banned substances. Guideline 2J in the NCAA Sports Medicine Handbook states, "Many athletes use nutritional supplements despite their having been proven ineffective. In addition, such substances are expensive and may be harmful to health or performance."